In the oil and gas industry, energy sources can be used to generate acoustic, seismic signals which propagate into the earth. These seismic signals can reflect from various interfaces between different underground formations, which formations have different acoustic properties. The reflected seismic signals can then be recorded by sensors, e.g., geophone/hydrophone sensors, for use in determining potential locations of underground hydrocarbon reservoirs of, for example, natural gas and oil. Once hydrocarbon reservoirs have been put into production, it is often desirable to be able to obtain ongoing seismic measurements to monitor characteristics of the underground hydrocarbon reservoir over time. For example, obtaining seismic data when (or before and after) injecting steam into the sand associated with the hydrocarbon reservoir may be desirable. Similarly, so-called 4D surveying, which adds a temporal dimension to the survey to show the status of hydrocarbon deposits over time, has recently become a popular tool to enable producers to more effectively extract hydrocarbons from their fields.
There are numerous examples of seismic surveying systems, both land and marine, which employ acoustic sources and receivers to image underground geologic structures. Complex processing algorithms are used to take the raw, received seismic signal data, and transform that data into images which can be used by those skilled in the art to determine where hydrocarbon reservoirs are likely to be located and how those hydrocarbon reservoirs change over time.
However, the generation and reception of acoustic signals has also been researched and implemented in fields of endeavor other than seismic surveying, such as various forms of sonar systems and arrays used by naval vessels. For example, as shown in FIG. 1, a submarine 2 is depicted with various sonar and receiving array systems. The submarine 2 shows an active system, e.g., a high frequency sonar system 4, as well as a plurality of passive systems, e.g., a towed array 6, a spherical array 8, a hull array 10 and a flank array 12. The flank array 12 is a relatively new type of array which allows for sonar sensors to be glued to the pressure hull of the submarine 2 while correcting for, e.g., noise and vibration issues associated with the generation and reception of acoustic signals proximate the pressure hull.
The example of the use of flank arrays shown in FIG. 1 can be described as an example of progress with respect to understanding and implementing the flank array technology in sonar and submarines. In a similar fashion, improvements have occurred over time in the use of acoustic signals in the oil field industry for seismic surveying. However, to date, flank array technology has not been implemented in seismic surveying equipment.